Last month federal agents raided the offices of two doctors, Dr Chae Hyun Moon, 55, chief of cardiology, and Dr Fidel Realyvasquez, 53, chief of cardiac surgery, at Redding Medical Center, Redding, northern California.
The FBI, in an affidavit supporting its raid on the doctors' offices, said it was gathering evidence as part of an investigation into claims that the two doctors performed hundreds of unnecessary invasive procedures, such as cardiac catheterisations, coronary bypasses, and heart valve replacements, to make money from Medicare, the federal government's health scheme for people aged over 65.
As many as a quarter to a half of the procedures may have been unnecessary, the federal affidavit contends. Despite many warnings over the years, hospital officials chose to ignore concerns raised by other doctors and a patient, Father John Corapi, 55, a Catholic priest, according to the people interviewed by the federal authorities.
The 230 bed hospital where the doctors work is one of the most profitable of Tenet Healthcare's 113 hospitals, because of its high volume cardiac programme.
Tenet Healthcare officials say that no charges have been brought against Dr Moon and Dr Realyvasquez, who continue to practise at the centre, though other doctors will now have to review any proposed procedures.
A spokesman for Tenet said that it was “deeply concerned by allegations filed by the US attorney's office in Sacramento.” It plans to retain independent experts to conduct its own internal investigation, in cooperation with the US attorney.